With motor vehicles there is the problem, in general, that outside stimuli of vibrations occurring during driving operation, such as when driving over uneven roadways, for example potholes or upwards projecting swells, can cause undesired vibrations and torsions of the chassis. Thus, driving safety and comfort can be impacted and the vehicle structure can be placed under strain. This problem occurs notably in cabriolet vehicles having an integral body-frame, which, due to the non-rigid roof, which especially in the open state cannot reinforce the chassis, have a stability disadvantage in comparison with closed vehicle bodies. In particular, noticeable torsions of the vehicle can occur around a longitudinal axis located in the direction of travel. In principle, the problem is more or less pronounced for all vehicle types.
It is known, in the underbody area to allocate separate, reinforcing struts to the chassis, of which, for example, one strut pair can extend from the outer edge area, in the vehicle transverse direction, in front of the rear wheel arch to an area lying further inward in proximity to a vertical vehicle longitudinal mid-plane behind the rear wheel arch, and can be fixed there to a spare wheel well provided with webs, beading, or similar bracing.
For vehicles with a low lying rear axle or other special geometric characteristics, the difficulty occurs that the struts usually lying horizontally under the bottom would hit on an obstacle, and the prior possibility of strut localization on the underbody is more difficult, or is completely impossible.
DE 102 14 372 C1 shows a vehicle in which two struts, which run toward the rear up to a vehicle transverse middle, are fixed with their backward ends on the chassis via a connection area. The connection area is, with respect to the vehicle longitudinal direction towards the back, fixed via three mounts to the chassis in proximity to the vehicle transverse middle. Thereby, the supports counteract a bending stress around a horizontal axis lying transverse to the vehicle. Additionally, a rear strut pair is provided, which likewise on one end is held at the connection area, and is intended to counteract a torsional stress of the vehicle about a vehicle longitudinal axis. However, for torsion the system is over-determined. Elongation or compression strains introduced via one of the forward struts are counteracted in part via a bending of the connection area, and in a further part via the supports lying in the vehicle transverse middle, where the supports on the basis of their proximity to the vehicle transverse middle offer no effective support against torsions, and only a further part of the introduced force is picked up by the struts. Therefore, the reduction of the torsions is degraded. In addition, for adverse chassis conditions, such as a low-lying rear axle, such a construction cannot be assembled.